Exhaust gas flow equalizer

ABSTRACT

The invention relates to an exhaust gas flow equalizer installed in an exhaust manifold and to an exhaust manifold with such an equalizer installed therein. The invention also relates to the manufacture and use of the exhaust gas flow equalizer and the exhaust manifold. The exhaust gas flow equalizer ( 2 ) according to the invention includes catalytic corrugated metal plates ( 2   f ) placed cross-wise to each other with the corrugation direction of their folds being in an angle towards the average flow direction of the exhaust gas (G) for equalizing the exhaust gas flow at least in the lateral direction.

TECHNICAL BACKGROUND

The invention relates to an exhaust gas flow equalizer installed in an exhaust manifold and to an exhaust manifold with such an equalizer installed therein. The invention also relates to the manufacture and use of the exhaust gas flow equalizer and the exhaust manifold.

A frequent problem in the exhaust gas treatment is that the exhaust gas flow is uneven in the exhaust piping. This causes problems in both the exhaust gas purification and the measurement of exhaust gas properties, and through this in the motor adjustment. Consequently, the modelling of the equipment operation also becomes difficult. Attempts have been made to resolve the problem by constructing separate equalizing equipment, which can have been connected in front of the catalyst, for example. Separate devices additionally cause increased counter pressure in the piping, which for its part reduces the motor power. This has proportionately special importance particularly in low power motors.

GENERAL DESCRIPTION OF INVENTION

A catalytic exhaust gas flow equalizer has now been invented, which equalizes the exhaust gas flow extremely efficiently for its entire volume.

To achieve this object, the invention is characterized by the features specified in the independent claims. Some of the preferable embodiments of the invention are set forth in the other claims.

An exhaust gas flow equalizer according to the invention is an equalizer to be installed in the exhaust manifold, covering essentially the cross-section of the entire installation site. The equalizer comprises catalytic corrugated metal plates placed cross-wise to each other with the corrugation direction of their folds being in an angle towards the average exhaust gas flow direction, for equalizing the exhaust gas flow in the lateral direction.

The exhaust gas equalizer is preferable in use because the pressure loss generated by it is relatively low in the exhaust manifold. This is due to the fact that a catalytic equalizer functions simultaneously both as an exhaust gas flow equalizer and catalyst.

In addition, the design of the equalizer is particularly simple and durable, because it is composed of one structural entity and can be efficiently connected to the casing of the exhaust manifold and/or integrated as a part thereof.

The exhaust manifold flow equalizer according to the invention also provides the advantage that the catalyst can be located as close as possible to the motor. In this case its catalytic startup/ignition is extremely quick.

According to one embodiment of the invention, the corrugation direction of the equalizer plates relative to the average exhaust gas flow direction is 5-90 degrees, such as 10-30 degrees. The installation angle to be selected depends on the desired degree of efficiency of the lateral mixture. It is possible to optimize the mixture or to minimize the pressure losses. In certain embodiments the installation angle relative to the average exhaust gas flow direction can be for example 15-25 degrees. This kind of equalizer produces efficient internal mixing of the exhaust gas flow while the flow resistance of the gas flow is relatively low at the same time. Furthermore, it should be noted that the equalizer according to the invention functions simultaneously as a catalyst, in which case the total flow resistance is preferably especially low.

An exhaust gas flow equalizer according to the invention can also be realized in such a way that the installation angle changes in the flow direction. For example, it is possible to manufacture a catalytic exhaust gas flow equalizer whose installation angle changes in the flow direction from 25 degrees to 20 degrees. Structural solutions can thus be utilized for optimizing the pressure loss and/or the flow equalization.

According to one embodiment of the invention, the exhaust gas flow equalizer has zones, whose catalytic coating and/or hole number differ from the other zones. The zone aspect can be implemented in one, two or three directions. For example, it is possible to preferably manufacture an exhaust gas flow equalizer in which the hole number is higher at the inlet channel, and correspondingly, the hole number between the inlet channels is lower, this arrangement thus allowing to further improve the equalization of the exhaust gas flow. The same can also be realized in the cross direction relative to the inlet channels.

The zone aspect can also be realized relative to the density of the coating, in which case a higher content of catalyzing agents is integrated to points with a higher load, such as at the inlet channel holes or the equalizer upper surface, for example in a situation, in which the exhaust gas flow direction is turned from the horizontal direction to below the car. The zone aspect can preferably also be realized in such a way that different zones have different catalyzing agents. This arrangement allows extremely versatile possibilities for adjusting the operation of the catalytic equalizer.

According to one embodiment of the invention, the exhaust manifold has a mixing chamber, whose casing is at least a part of the exhaust manifold casing. The manufacture of such a mixing chamber is preferable as it can be manufactured in connection with the exhaust manifold manufacture. The mixing chamber can preferably be located between the inlet channels, which allows partly mixing together the exhaust gas flows coming from different inlet channels. This arrangement enables a reliable use of a lambda sensor, for example, for the adjustment of combustion. In addition, the mixing chamber makes the equalization of the exhaust gas flow generally more efficient.

According to one embodiment of the invention, the exhaust manifold additionally has one or more catalysts connected thereto, which have been installed in the mixing chamber after the exhaust gas flow equalizer relative to the gas flow direction. For example, it is possible to manufacture an exhaust manifold, which has catalytic exhaust gas flow equalizers in the inlet pipes and a separate catalyst in the connecting part. This separate catalyst can be different from or similar to the exhaust gas flow equalizers as for the design.

According to one embodiment of the invention, the exhaust manifold additionally has one or more additional equalizers connected thereto. In certain embodiments it may be necessary to adjust the exhaust gas flow particularly evenly. The separate equalizer can preferably be a mesh or a rough metal wool, for example. The separate additional equalizer can be located before or after the actual equalizer.

The equalizer according to the invention suits well to various applications. It can be used in motors using various fuels and in applications of various sizes. It is particularly suitable for example in motors with a relatively low power, such as motors whose number of cylinders is 2.

DETAILED DESCRIPTION OF INVENTION

Some of the embodiments of the invention are described below in detail by making reference to the enclosed drawings.

FIG. 1 is a sectional view of an exhaust manifold.

FIG. 2 is a sectional view of another exhaust manifold.

FIGS. 3 and 4 illustrate exhaust gas flow retention distributions in the exhaust manifolds.

FIGS. 5 and 6 illustrate exhaust gas flow speed distributions in the exhaust manifolds.

FIG. 7 shows the exhaust gas flow zones in the exhaust manifold.

FIG. 1 shows an exhaust manifold 1, having an exhaust manifold flow equalizer 2 installed to the connecting part 7. The exhaust gas flow equalizer comprises 2 catalytic corrugated metal plates 2 f placed cross-wise to each other (shown as examples) with the corrugation direction of their folds being in an angle towards the average flow direction of the exhaust gas G, for equalizing the exhaust gas flow at least in the lateral direction. The exhaust manifold has an exhaust gas flow mixing chamber 4, whose casing 4 c is a part of the casing 1 c of the catalyst 1. Exhaust gas G flows in the exhaust manifold 1 from the inlet channels 3 partly through the mixing chamber 4 to the exhaust gas flow equalizer 2 and further to the outlet channel 5.

FIG. 2 shows an exhaust manifold 1, having exhaust manifold flow equalizers 2, 6 installed to the connecting part 7 and to the inlet channels 3. The exhaust gas flow equalizer 2 comprises catalytic corrugated metal plates 2 f placed cross-wise to each other (shown as examples) with the corrugation direction of their folds being in an angle towards the average flow direction of the exhaust gas G, for equalizing the exhaust gas flow at least in the lateral direction. The corrugation direction of the folds is in a varying angle relative to the average gas flow G direction such that at the center of the exhaust manifold the angle is lower than at the edges. The exhaust manifold has an exhaust gas flow mixing chamber 4, whose casing 4 c is a part of the casing 1 c of the catalyst 1. Exhaust gas G flows in the exhaust manifold 1 in the inlet channels 3 through the exhaust manifold flow equalizers 6 partly to the mixing chamber 4 and to the exhaust gas flow equalizer 2 and further to the outlet channel 5.

FIGS. 3 and 4 illustrate the exhaust gas flow retention distribution in two different exhaust manifolds 1. In FIG. 3 the exhaust gas flow equalizer 2 is installed at the center of the connecting part 7 while in FIG. 4 it is installed in the bottom part of the connecting part 1C. FIGS. 5 and 6 illustrate the exhaust gas flow speed distribution in two different exhaust manifolds 1. In FIG. 5 the exhaust gas flow equalizer 2 is installed at the center of the connecting part 7 while in FIG. 6 it is installed in the bottom part of the connecting part 1C. Exhaust gas G flows in the exhaust manifold 1 from the inlet channels 3 partly through the mixing chamber 4 to the exhaust gas flow equalizer 2 and further to the outlet channel 5. FIGS. 3-6 illustrate well that the exhaust gas flow equalizer 2 has equalized the exhaust gas flow variations mixing together the gases coming from both inlet channels 3.

FIG. 7 shows an exhaust gas flow equalizer 1 according to FIGS. 3 and 5 installed at the center of the connecting part 7 having different zones 2A, 2C for equalizing the load of the exhaust gas G. Exhaust gas G flows in the exhaust manifold 1 from the inlet channels 3 partly through the mixing chamber 4 to the exhaust gas flow equalizer 2 and further to the outlet channel 5. Zones 2A have a lower exhaust gas flow speed than zones 2C and correspondingly, the substrate content created for zones 2A is lower than for 2C. This arrangement allows effective optimization of the operation of the catalytic equalizer 2. 

1-19. (canceled)
 20. An exhaust gas flow equalizer having at least two exhaust gas inlet channels (3) to be installed in an exhaust manifold, characterized in that the exhaust gas flow equalizer (2) comprises catalytic corrugated metal plates (2 f) placed cross-wise to each other with the corrugation direction of their folds being in an angle of 10-30 degrees towards the average flow direction of the exhaust gas (G) and that the exhaust manifold (1) has between inlet channels (3) one or more exhaust gas flow mixing chambers (4), whose casing is at least a part of the exhaust manifold casing.
 21. An exhaust gas flow equalizer according to claim 20, characterized in that the corrugation direction of the folds of the corrugated metal plates (2 f) is in an angle of 15-25 degrees relative to the average exhaust gas (G) flow direction.
 22. An exhaust gas flow equalizer according to claim 20, characterized in that the exhaust gas flow equalizer (2) has zones (2A, 2C) whose catalytic coating differs from each other.
 23. An exhaust gas flow equalizer according to claim 20, characterized in that the exhaust gas flow equalizer (2) has zones (2A, 2C) whose hole number differs from each other.
 24. An exhaust gas flow equalizer according to claim 20, characterized in that the corrugation direction of the folds of the corrugated plates (2 f) changes in the flow direction (G), such as from 25 degrees to 20 degrees.
 25. An exhaust gas flow equalizer according to claim 20, characterized in that the exhaust manifold (1) has additionally one or more separate catalysts connected thereto.
 26. An exhaust gas flow equalizer according to claim 20, characterized in that the exhaust manifold (1) has additionally one or more separate exhaust gas flow equalizers connected thereto.
 27. Motor exhaust manifold, characterized in that it comprises one or more exhaust gas flow equalizers (2) according to claim
 20. 28. The exhaust manifold according to claim 27, wherein the one or more exhaust gas flow equalizers (2) are installed in the inlet chamber/chambers (3).
 29. An exhaust manifold according to claim 27, wherein the one or more exhaust gas flow equalizers (2) are installed in a connecting part (7).
 30. The exhaust manifold according to claim 27, wherein the one or more exhaust gas flow equalizers (2) are installed in an outlet channel (5).
 31. The exhaust manifold according to claim 27, wherein a lambda sensor is connected to the exhaust manifold (1).
 32. A method for manufacturing an exhaust gas flow equalizer having at least two exhaust gas inlet channels (3) to be installed in an exhaust manifold, characterized in that the exhaust gas flow equalizer (2) is manufactured by connecting to each other catalytic corrugated metal plates (2 f) placed cross-wise to each other with the corrugation direction of their folds being in an angle of 10-30 degrees towards the average flow direction of the exhaust gas and that one or more exhaust gas flow mixing chambers (4), whose casing is at least a part of the exhaust manifold casing, is composed to the exhaust manifold (1) between said inlet channels (3).
 33. The method for manufacturing an exhaust manifold, characterized in that one or more exhaust gas flow equalizers (2) according to claim 20 are installed to an exhaust manifold. 